Greece will raise €3 billion ($4.14 billion) from its first longer-term bond sale in four years after attracting more than €20 billion of demand, according to bankers working on the deal.

The bankers said the five-year bond would price to yield 4.95%—a sharply lower price tag than initial suggestions in the range of 5.25% to 5.5%. About 550 investor accounts placed orders, they added.

To a degree, the sale is symbolic: Greece regularly raises more than €1 billion each month through the auction of 13-week and 26-week T-bills, and the bulk of the government's financing comes through rescue loans from its eurozone peers and the International Monetary Fund.

But a successful sale will be a small step toward weaning Greece from that aid. The eurozone's assistance is scheduled to end this year, though a relatively small amount of IMF aid will continue.

The sale also reflects a shift in capital markets since 2012, when Greece defaulted on €200 billion of debt and saddled private investors with large losses. In those days, Greece was all but untouchable. The new, long-term bonds it gave investors in its restructuring sported yields of close to 20% and were the province of risk-loving hedge funds.

Earlier Thursday, a powerful bomb exploded in central Athens, causing no injuries but some damage. The timing and the location of the blast—just a block away from the headquarters of Greece's central bank—was seen as a symbolic protest against the coming bond issue, but two persons familiar with the deal said the issue would go ahead as planned.

The explosion was preceded by two anonymous calls to a Greek newspaper and a news website warning that a car packed with 75 kilos has been left outside the central bank's building.

Police cleared the area immediately and 45 minutes later the explosion followed, according to a police official.

Write to Ben Edwards at ben.edwards@wsj.com, Alkman Granitsas at alkman.granitsas@wsj.com and Nektaria Stamouli at nektaria.stamouli@wsj.com

—Katie Martin and Neelabh Chaturvedi in London contributed to this article, which was first published by The Wall Street Journal